About our Celtic Ancestry report

What is the Genomelink Celtic Ancestry report?

This Celtic Ancestry Report combines cutting-edge genetic science with archaeological data to illuminate your connection to the ancient Celtic world, from broad ancestral affiliation down to individual Iron Age figures. Whether you're matched with a Hallstatt warrior or a La Tène matriarch, each layer of this report is built to tell a deeper story about your roots.

How does Genomelink Celtic Ancestry calculate your Celtic ancestry estimate?

What is the Celtic Index?

The Celtic Index represents how much of your genome aligns with ancient Celtic populations. For example, a Celtic Index of 68.69% means over two-thirds of your DNA shows strong similarity to ancient Celtic individuals from across Europe.

How is it calculated?

 We use a PCA (Principal Component Analysis) approach, which is widely accepted in ancient DNA research. PCA reduces your genetic data into a few key coordinates based on hundreds of thousands of SNPs. We then compare your coordinates against a custom-built reference panel that includes ancient groups such as:
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• Celts
• Germanic tribes
• Illyrians
• Slavs
• Iberians
• Other non-European populations

To avoid skewed results due to degraded ancient DNA, we apply t-SNE clustering to filter out outlier samples with missing data. Finally, we use a distance-based power scaling method, where your proximity to each group’s centroid determines your Celtic percentage. This method is more accurate for distinguishing between closely related European populations than standard admixture tools.

⚠️ Note: This method works best when the user has substantial European ancestry. Accuracy may drop if European DNA makes up only a small portion of your genome.

How should I interpret the Celtic Index? How does the % differ from the % of ethnicity estimate in modern ancestry reports like Deep Ancestry or AncestryDNA?

Celtic Index specifically represents the percentage of Celtic ancestry (in terms of genetic distance) present in your DNA when compared to a set of ancient Celtic samples curated from peer-reviewed scientific articles. 

The percentages in modern (like our Deep Ancestry report) and ancient ancestry analysis results will differ due to the distinct methodologies and reference datasets used for each type of analysis. Modern ancestry focuses on recent genetic heritage, tracing up to 10 generations with detailed algorithms and extensive, current reference populations.

In contrast, ancient ancestry delves into your distant past, relying on limited ancient DNA samples that represent populations from thousands of years ago.

Both types of analysis are subject to change as DNA analysis techniques improve and new ancient samples are discovered. Modern ancestry results reflect recent genetic contributions, while ancient ancestry results highlight deep ancestral origins. These differences provide complementary insights into your genetic heritage, from recent centuries to ancient times.

What is the difference between modern and ancient Celtic? Does 0% Celtic Index mean I have no modern Celtic ancestry roots? Or Does a positive Celtic Index mean I also have modern Celtic ancestry roots?

The term Celtic can refer to many things—language, culture, and genetics—across different time periods.

The Celtic Index in this report specifically measures how closely your DNA matches ancient individuals from Iron Age Central Europe (Hallstatt, La Tène, Gaul). These ancient populations are often labeled Continental Celts.

However, modern Celtic identity—as seen in regions like Ireland, Scotland, and Wales—developed through additional historical and genetic layers over time. These include influences from the Atlantic Bronze Age, early farmers, Vikings, and others. Because of this complexity, a 0% Celtic Index does not mean you lack modern Celtic roots—it simply means your DNA didn’t align closely with the ancient samples we analyzed.

Conversely, a positive Celtic Index means your DNA has similarities to these ancient Continental Celtic groups, but that doesn’t necessarily guarantee modern Celtic identity. It’s one piece of a much larger ancestral picture.

Why is my DNA match at 0% while I have a positive Celtic Index?

The Celtic Index is based on genome-wide similarity to cultural clusters, while individual DNA matches are based on direct comparison to single ancient genomes. If your similarity is spread out across many individuals, or below the reporting threshold for any one sample, your overall Celtic percentage may still be positive—even if individual matches show as 0%.

I have many ancestors from the Irish and British, but the Celtic index is 0%. How could this happen?

This is an important distinction. The Celtic Index in this report is based on Continental Celtic (and very limited Insular Celtic) archaeological cultures—Hallstatt, La Tène, and Gaul—which mainly represent Iron Age groups in Central Europe. These are genetically and geographically distinct from the Insular Celts of Ireland, Scotland, and Wales.

People with ancestry from the British Isles may have strong Celtic cultural or linguistic heritage, but genetically, they often reflect complex layers from the Atlantic Bronze Age, early Neolithic farmers, and later migrations—not just the Continental Celtic gene pool we focus on here. So a 0% Celtic Index doesn’t mean you don’t have Celtic roots—it just means your DNA doesn’t align closely with the ancient  Celtic samples currently available. Future research may help bridge this gap more clearly.

I have many ancestors from Portugal, but the Celtic index is 0%. How could this happen?

While Celtic cultural and linguistic influence did reach the Iberian Peninsula—especially through groups like the Lusitanians and Celtiberians—our current Celtic Index is based on ancient DNA from archaeological sites associated with Continental Celtic cultures like Hallstatt, La Tène, and Gaul. These samples primarily come from Central and Western Europe (e.g., modern France, Germany, Austria), and unfortunately, ancient DNA from Celtic-associated Iberian sites is still limited in public datasets.

So, a 0% Celtic Index doesn’t mean there was no Celtic influence in your ancestry—it simply means your DNA doesn’t closely match the specific ancient samples we currently use in this report. As more Iberian Celtic samples become available in the future, we hope to better capture that regional heritage.